Survival rate at day 28, percentage of patients requiring who did not require RRT in the "delayed" strategy, time until cessation of RRT therapy, rate of adverse events potentially related to the AKI or to RRT (e.g; RRT catheter-related complications, hemorrhage due to anticoagulation required for RRT etc…), rate of nosocomial infections, number of ventilator-free days of RRT-free days and of vasopressors free days, length of stay in ICU and hospital, rate of limitations of treatment for futility, total cost of consumables (including RRT catheters and lines among others) related to RRT between day 1 and day 28.